Yarn heat treating process

ABSTRACT

An improved method for heat setting, dyeing and fixing of fibers in a continuous operation under a controlled elevated temperature and pressure steam environment in an enclosed system.

United States Patent 1191 Dunn 1451 Nov. 11, 1975 r 1 1 YARN HEAT TREATING PROCESS [76] Inventor: HaroIdH. Dunn, 2362 Kings Point Drive, Atlanta, Ga. 30341 22 Filed: Jan.22, 1973 21 AppI. No.: 325,731

[52] US. Cl. 8/l49.1; 8/149.3; 8/1512; 68/D1G. 1; 68/5 E [51] Int. CI. D06B 3/04 [58] Field of Search 8/1491, 149.3, 151, 151.2; 68/5 C, 5 D, 5 E, DIG. 1, 205 R, 18 C;

[56] References Cited UNITED STATES PATENTS 2,567,938 9/1951 Hoffman 68/205 R 2,905,522 9/1959 Fahringer 68/5 E X 3,478,546 11/1969 Serbin 68/5 E 3,701.269 10/1972 Wilcox 68/205 R X 3.726.640 4/1973 Takriti et a1. 8/1491 X FOREIGN PATENTS OR APPLICATIONS 1,105,062 3/1968 United Kingdom 68/5 D Prinuu E.\'mninerHarvey C. Hornsby Assistant ExaminerPhi1ip R. Coe

Attorney, Agent, or FirmCushman, Darby & Cushman [57] ABSTRACT An improved method for heat setting, dyeing and fixing of fibers in a continuous operation under a controlled elevated temperature and pressure steam environment in an enclosed system.

11 Claims, 6 Drawing Figures US. Patent Nov. 11,1975 Sheet2of5 3,918,111

U.S. Patent Nov. 11, 1975 Sheet 3of5 3,918,111

U.S. Patent Nov. 11, 1975 Sheet4 015 3,918,111

U.S. Patent Nov.11 1975 SheetSofS 3,918,111

YARN I-IEAT TREATING PROCESS This invention relates to a method of continuously dyeing with solid or multi-colored dyes of fibers such as synthetic yarn in an enclosed system under a controlled elevated temperature and pressure saturated steam environment which normally are resistant to dyeing by conventional means well known in the art such as described in US. Pat. Nos. 814,124 and 3,614,798, and

British Pat. No. 1,164,852. Also, it has been found that heat-setting fibers by subjecting them to heat treatment with steam under various conditions are described in US. Pat. Nos. 2,873,597; 2,584,043; 2,398,856 or 3,213,470, and thereafter dyeing said treated fibers, particularly polyesters, by conventional means produces poor results. Thus, in the industry synthetic yarns used to produce tufted carpets are normally dyed one color by either stock dyeing, colored during the fiber making process, mass dyed on spools after yarn manufacture, beck bath dyeing after tufting into greige carpet, or dyed on ranges after tufting. Where multi-colored dyeing is desired, other methods are used such as by the printed pattern, differential dyeing, splatter and space dyeing methods and the like.

Although some synthetic fibers such as nylons lend themselves to dye fixation at atmospheric steam temperatures, other fibers such as the polyesters do not, and therefore require expensive chemical carriers to force or accelerate the reaction, making the processes difficult to handle and very costly, and the results are generally poor. Also, even with such fibers as nylon, which as pointed out above lend themselves to dye fixation at atmospheric steam temperatures, they require a heat set treatment prior to dyeing.

It is a further object of this invention to heat set, dye, fix and wash yarn strands which enter the enclosed system dry and exit in a washed clean condition without being exposed outside the machine. It is also the object of the present invention to provide a cascade washer within the closed system to provide more economical use of wash water. The use of recycled condenser water and the recovery of waste heat of the enclosed system improve the economic use of energy in the present invention.

It is also an object of this invention to continuously heat set and dye various synthetic fibers and yarns at elevated temperature and pressure in a saturated steam environment.

Another object of the invention is to heat set synthetic fibers during the same operation as dyeing and at essentially the same temperature.

Another object of the invention is to provide a means and method of providing a pressure seal for entering a steam pressurized enclosure without damage to the yarn using the pressure drop due to flow friction and by forced condensation of escaping steam by heat loss through yarn tubes to the circulated cooling water or fluid.

It is also an object of the invention that once inside the enclosure, the yarn can be subjected to various processes such as solid dyeing in one color, multi-color dyeing in programmed sequences, application of desired process chemicals, and heat setting synthetic yarn fibers.

It is further an object of the invention to provide a method of establishing a pressure sea] as an exit from the pressurized steam atmosphere after the processes 2 are completed similar to the entrance pressure seal method above.

Still another object of the invention is to provide a method of washing excess dyes and/or chemicals from the yarn utilizing the water source available from the entrance and exit thermodynamic pressure seals, with provision for economical recovery of waste heat.

Still another object of the invention is to continuously dye fibers, yarns and/or strands at essentially elevated fixation temperature to effect improved dyeing.

Still another object of the invention is to maintain during the dyeing and fixation phases, steam at saturated steam conditions, regardless of the steam pressure, and maintaining either constant or slightly gradually rising steam temperature during the fixation phase.

Still another object of this invention is to provide a process for effecting solid or multi-color dyeing, heatsetting, dyeing and dye fixation by maintaining and controlling the temperature-pressure levels within any desired limits such as at temperatures from about 250F to about 400F and at corresponding pressures of saturated steam, wherein the entire process is carried out in an enclosed system.

Other objects will be apparent from the description and the drawings as set forth hereinbelow.

These and other objects are accomplished by continuously heat setting, dyeing and dye fixing of various synthetic yarns, fibers, strands and the like in an enclosed system under an elevated temperature and pressure saturated steam environment.

FIG. 1 is a simplified drawing in section of the apparatus desired for carrying out the dyeing process of the present invention;

FIG. 2 is a detailed section of the apparatus wherein the fibers or yarns are pre-treated prior to being subjected to heat-setting and dyeing;

FIG. 3 is a detailed section of the dyeing section of the apparatus;

FIG. 4 is a cross-section along line 44 of FIG. 1;

FIG. 5 is a detailed section of the apparatus wherein the fibers or yarns exiting from the apparatus of FIG. I enter the after coolers and washer-condenser; and

FIG. 6 is a detailed section of the apparatus wherein the fibers or yarns exiting from the apparatus of FIG. 5 enter the final phase of the washer-condenser.

Referring to FIG. 1, fibers, filaments, yarns, strands, ropes, etc., hereinafter referred to as yarn l0, enters at 11 into a saturator box 12 wherein said yarn can be directed via rolls 13 through a pre-wet solution 14 or the yarn can be directed directly into enclosed tube 15 via 13a which leads and separates the yarn through condenser 16; the saturator box 12 is separated from condenser 16 by baffle 17. It is obvious from the description of the present invention that the present apparatus can be easily adapted for any number of yarn ends in yarn strand 10, for example, up to or more. Furthermore, groups of machines can be operated in tandem for large production, or one machine adpated for two or more groups of separately travelling yarn strands l0. Enclosure tube 15 connects with tubes 18 which run through heat exchanger assembly 19 to direction roll 20 located in section 21 and back. through tubes 18 in heat exchanger 19 to condenser assembly 16. The yarn strands are then directed through tubes 18 in heat exchanger 19 via roll 22 to roll 23 and into steam manifold 24 in communication with valved steam line 25 and into the dye chamber 26 where said yarn is propelled and guided by various groups of driven rolls 27. It should be understood that the num ber and length of passes through the pressure seal (heat exchanger) at both entrances and exit ends are determined by the maximum specified enclosure pressure being sealed against. The higher the pressure differential, the larger the flow resistance required. The yarn tension and speed throughout the machine can be preset and controlled to meet various dyeing requirements.

FIG. 2 is a detailed section of sections 12 and 16, said condenser section 16 being separated from the heat ex changer 19 and saturator box 12 by baffles 17 and 30. In said saturator box 12 are driven rolls 13 which guide the strands down through pre-wet solutions 14, such as water or solutions containing penetrants, ionic, anionic and/or cationic wetting agents and preferably watersoluble wetting agents, pH correctors, etc. The pre wetting step can be eliminated by passing the strands or fibers or yarns directly to enclosure tube 15. The quan' tity of the wet-out solution can be maintained by suitable level control means and a spring loaded squeeze roll 13a is used to remove excess pick-up.

The condenser 16 has injection means 30a for injecting water via nozzles 71 into the condenser 16 for effecting cooling and the condensed liquid removed by line 72.

Steam, at desired saturated temperature and pressure, enters 24 via line 25 which contains pressure control valve 29 and into steam header 25a which is equipped with a safety pressure relief valve and block valve 29a; the steam is then directed into 24 and into dye chamber 26 via orifice 31. lt is also possible to omit the condenser 16 by including an equalizer pipe (not shown) connecting the cavity around roll 23 with the condenser-washer 130.

FIG. 3 is a detailed section of steam manifold 24 and dye chamber 26. The steam enters the dye chamber 26 wherein the pressure is controlled by valve 29 so as to maintain it at a desired constant pressure. The steam pressure in 26 should be slightly lower than in header 25a and manifold 24 pressure by the amount of pressure drop through 29, entrance losses at manifold 24, and pressure drop across orifice 31.

Returning to FIG. 1, the strands or yarn pass through 24 via a yarn tube 32, said manifold 24 having at the delivery end of tube 32 an orifice (venturi) 31, into the dye chamber 26.

The pressure at the throat of the orifice (venturi) 31 should be less than either the manifold 24 pressure and the dye chamber 26 pressure under normal and constant operation, and the pressure inside the yarn tube 32 delivery end should be equal to this pressure. With saturated steam, the throat pressure can approach theoretically only to 57% of the upstream pressure because of the critical velocity characteristics of flow of compressible fluids. The dye chamber 26 pressure should approach manifold 24 pressure because of the relationship h, V /2g h, V /2g h Constant. The pressures will never equalize as long as there is flow through orifice 31 because of the loss of kinetic energy due to friction and turbulence. Thus, yarn l enters at the minimum pressure in the chamber and this pressure differential is a function of nozzle design.

Steam is made to flow in the opposite direction to yarn traveling through yarn tubes 32 into draw-roll chamber 34 and subsequently all the way to machine entrance I] forced by the pressure differential from dye chamber to atmospheric pressure at the entrance.

The stream in the opposite direction does not flow I given location; (2) the forced condensation by heat loss to the circulated water outside the yarn tubes 18 in heat I exchanger 19 as supplied by a pipe (not shown), and (3) the condensation produced by contact with water sprays in condenser 16. The steam pressure at theintermediate location 21 having a cavity therein not shown is bled off. and directed outside over to a washer-con denser through a pipe and this bled steam reducesthe pressure in 21 and is fully condensed via the washer condenser system. By control of heat transfer within exchanger 19 and in condenser 16, the pressure in the yarn tube 15 is reduced to atmospheric. Condensate is collected and bled off at the bottom 72 of condenser 16 and use for yarn washing.

Thus, the yarn continuously leaves atmospheric pressure and enters elevated saturated steam pressure; the steam escape is prevented and heat produced from this steam is made available for recovery and reuse as desired.

Valve 29 serves to shut off the steam supply to the process chambers and is mechanically connected to a quick pressure relief valve (not shown) so that theoperator can stop the steam supply and reduce internal pressure quickly to atmospheric before opening access hatches to the pressure area.

The dyeing operation can involve various continuous dyeing methods located in the pressure chambers 26 and 26a. Thus, these methods include:

a. Single color bathpadtype and squeeze b. Single color dye injection 0. Multiple color dye injection Any of the above can be used in a continuous application of dyes for solid color as the end result or asa solid color ground shade for subsequent multi-color patterned application (space dyeing) performed at a later time within the pressure chambers.

A. Single Color Pad-Dye Method. Yarn enters dye chamber 26 propelled by motor driven rolls 27 against the yarn tensioning force caused by a steam pressure differential between orifice 31 and draw-roll chamber 34. Yarn enters at approximately the same temperature as saturated steam in the dye chamber, thus eliminating yarn thermal shock. Yarn temperature has gradually increased from the temperature of the wet-out solution in saturator box 12 to the temperature of dye chamber A liquid quantity of dye mixture 35a is supplied by an external pump of sufficient discharge head (not shown) into the lower portion of dye chamber 26. The level of quantity of dye mix can be controlled by automatic throttling of the external supply pump either by manual flow adjustment, by photoelectric means, by a differential pressure transmitter sensing the head of dye mix and signaling supply valve position or by other common methods of feed and level control.

Yarn is directed through the dye mix on rolls 27 into and out of the liquid dye mix and subsequently through the spring loaded squeeze rolls 36 for excess dye mix removal and padding action. This yarn for the single color pad-dye method by-passes the dye injection device 38.

The dye mix preferably should be supplied as hot as atmospherically possible to prevent dilution from condensate within the dye chamber. The dye mix should not boil and evaporate in the dye chamber because of the saturation pressures involved. If dye mixes due to chemical reasons boil at relatively reduced temperatures, inert detergents may be added to raise the boiling point of the dye mix. Anti-foam agents can also be added if desired. A drain (not shown) equipped with a valve allows the dye mix to be discarded, and therefore, the entire dye chamber 26 can be washed out via access hatch 37 at a relieved pressure upon the need for a dye color change.

The yarn leaves squeeze rolls 36 and is directed into fixation chamber 78 via yarn tubes 79.

B. Single Color Dye Injection Method. As an optional method of introducing the dye mix to the yarn, the yarn upon entering dye chamber 26 is directed via driven rolls to dye injection head 38 which may be a block of stainless steel with a smooth hole sized for a snug fit to the yarn strand passing through. The dye mix is pumped by an external supply pump operating at required constant head pressure onto and into the passing yarn via two or more properly sized injection ports drilled in the injection head block 38 in the range of 15 to 90 against the yarn travel. The supplied dye mixture at higher pressure than within the dye chamber forces the liquid dye mix into the fibers of the yarn strand. Common accurate flow controls insure a correct amount of dye mixis injected according to yarn travel speed and yarn demands. The dye mix is supplied to head 38 via tubes 39 from dye manifold 40. In this mode of operation the level of dye liquid 35a previously described does not exist; however the direction rolls normally used for immersion are used to mechanically work the injected dye liquid onto the yarn structure uniformly. The squeeze rolls 36 also assist.

C. Multiple Color Injection Method. If desired, a second, or more, color can be sequenced into the traveling yarn by duplicating the injection head 38 and distribution pipes 39 and 40. The selection of dye injected at any instant is determined by which system is pressurized with dye mix by the external supply pumps via the block valves 41. By alternating the opening of valves (not shown) connected to line 41, the yarn can be dyed different colors. This color change is intended for relatively infrequent switching and is intended to offer more space dyeing color patterning from subsequent multi-color space dyeing.

If only one solid color ground shade is desired, only one dye injection head is used or the yarn is dyed by previously described pad-dye optional method. If dual, or more, colors of ground shade are desired for greater space dye latitude then more than one injection head can be employed at this point. 1

Dyes react to the yarn structure at a speed determined by time-temperature relationships. Yarns upon completing the travel through dye chamber 26 and having absorbed mechanically sufficient dye mix are directed into yarn tubes 79. The steam conditions inside these tubes do not vary appreciably from that of dye chamber 26. Yarn travels at constant speed through these tubes with direction changes being effected by rolls 36 and rolls 27. The fixation time required sets the required number of passes in tubes 79 and the length of the fixation chamber.

The yarn tubes are located inside fixation chamber 78 but the yarn is exposed only to conditions within tubes 79. Outside the yarn tubes but contained by en closure 78 is steam at about the same conditions, i.e., temperature-pressure, as the steam supplied via manifold 24 to dye chamber 26 except that the pressure and temperature are slightly higher due to friction losses through valve 29, manifold 24 and orifice 31. This slightly higher temperature prevents condensation inside the yarn tubes and is, therefore, desirable. An air vent (not shown) eliminates colder air pockets from the fixation chamber.

The steam supplied to fixation chamber 78 also is supplied to the identical fixation chamber 43 via connection 44. Steam consumption for both these chambers is'a function of shell heat loss to the room; these surfaces are, therefore, insulated in order to reduce any heat losses. Similarly, other heat radiating surfaces may be insulated to reduce the unwanted heat loss if desired. Condensate is accumulated in sump 45. The steam supplied to vessels 78 and 43 never touches the yarns but serves to produce a constant temperature environment within the contained yarn tubes 79 and 48. The dyes applied previously in dye chamber 26 are now fully reacted and fixed to the traveling yarns and the yarns are now ready for additional patterned multicolor space dye operation.

If, however, only solid color yarn dyeing is desired, the subsequent multi-color dye injection of dye chamber 50 can be bypassed and the fixation chamber 43 is used as an extension of chamber 78 to allow faster production speeds because of longer available reaction space-time.

Steam flow rates through fixation chambers 79 and 43 are low and constant and are effected only by the heat loss condensation rates of dye chambers 26 and 50 and from the forced flow to and through the subsequent aftercooler and washer-condenser shown in FIGS. 5 and 6. The steam temperature will be slightly higher (possibly slightly super-heated) in final chamber 52 due to the small amount of heat added to the process steam during flow through fixation chambers 79 and 43, but this may be offset due to the fact that injected dyes are somewhat cooler. The pressure at final chamber 52 may be slightly less due to friction, even at the low flow rates through fixation chambers.

Yarn strands enter space dye chamber 50 via yarn tubes 79 through fixation chamber 78 with solid ground shape dye previously applied and fully fixed. Yarn is propelled by driven rolls 53 to traction roll 54. Yarn strands during this travel can be divided into a smaller number of ends and more strands. Yarn 10 enters under tension a space dye injection block (not shown) in chamber 50 that is identical to previously described injection blocks 38 except perhaps for minor design changes to provide for a smaller number of ends for more control end-to-end of precise dye injection. Any reasonable number of injection blocks can be installed, each handling a different and separate dye color and having a separate supply pump system. Dye feed pipes and dye manifolds and control valves similar to those of solid dye injections 39, 40, 41, respectively, are present in 50. Operation is similar to that previously described. Only one color system is controlled by a sequencing pattern repeatable controller device geared to the yarn speed. Such a device can be of many types and includes such device as cams with roller limit switch followers, programmers using perforated cards or tapes, magnetic tapes, etc. The most simple device comprising a cam/- switch arrangement is usually best for most applications of this invention since the normal color patterns are not that complex. The device can be driven directly from the machine drive components so as to track at varying machine yarn speeds. The entire series of dye injectors can be by-passed as shown for solid shade dyeing operation. Any build-up of excess dye mix and condensate from walls of enclosure 50 is accumulated and discarded to drain via a trap not shown.

Any practical number of colors can be programmatically injected into the yarn strands. The yarn, still exposed to elevated temperature-pressure as supplied via tube 79, is now ready to enter the secondary fixation chamber 43 via tubes 48 along with the applied wet dye mix in a similar manner to the predescribed solid dye operation. Access hatch 60 allows access to the yarns and devices when internal pressure is relieved. A hatch not shown can support the space dye injectors and allow the entire unit to be removed.

The yarn enters and leaves the fixation chamber 43 in a manner identical to that of chamber 78 via tubes 48 enclosing the yarn and directing the steam flow to final chamber 52 which is maintained at a constant steam temperature and pressure from preceding upstream sections. The yarn is directed and propelled by driven rolls 62. A final chamber sump accumulates and dispenses to a drain any condensate from walls via a suitable trap (not shown).

Heat setting of the yarn may take place at the same time as the yarn is dyed in this elevated temperature pressure system. Nylon yarns heat set under high tension tend to have less bulking and are used mostly for knitting and weaving, whereas nylon yarns heat set under low or zero tension conditions give a suitable bulky yarn for carpets. Thus, the present invention also contemplates the use of a varied yarn tension heat setting device in place of chambers 78 and 43. Yarn is allowed to accumulate on a slowly traveling mesh conveyor while still exposed to an even higher ambient temperature by slight superheat of the steam at this location, followed at the delivery end by a hot water spray quench just prior to the yarn exiting the pressure enclosure through the aftercooler tubes. This heat sets the yarn in a very relaxed manner.

With this design the heat setting can be achieved with adjustable yarn tension from slack, or zero tension, all the way up to the tensile limits of the yarn strands.

FIG. 4 is a cross-section along line AA of FIG. 1 and shows the interior design of tubes 48 and chamber 43. The heat exchanger 19 and the fixation chamber 79 are also similar.

Referring to FIG. 5, the yarn travels from exit tube 63 to' primary aftercooler 101 via thru tube 102. The primary aftercooler 101 can be filled with circulating cooling water entering through connection 98 and exiting through pipe 99. The cooling water for this aftercooler can be obtained from the heat exchanger 19. Steam from final chamber 52 also enters tubes 63 and 102 along with the yarn travelling in the same direction. A portion of the total heat of this flowing steam is transferred by conduction to the aftercooler circulating water. Friction also reduces the pressure as the steam and yarn both enter direction box 104 with yarn guided by roll 105. Trap 106 collects and discharges any condensate to the drain.

The yarn passes through intermediate chamber 107 without exposure, via tube 108 with a pressure-tight 8 1 connection to tube 109 located in a multi-pass arrangement through secondary aftercooler 110, the yarn subsequently passing to condenser header box 112. The

secondary aftercooler is only optional and is not necessary for the proper operation of the present invention;

The steam travels along with yarn all the way from final chamber 52 until both reach the condenser header box 112. This steam entering this route at yarn tube 63 drops in heat content throughout this travel by heat exchange to the aftercooler circulating water; the pressure of the steam drops from exit and entrance losses at I the various tube ends and from friction within the.

tubes. This heat transfer from the drop in steam entropy to the circulating cooling water is recoverable heat as described later. The yarn with the dyes fixed enters condenser header box 112 carrying the water applied with the dyes during the dyeing operations plus any supplementary water from condensation picked up.

during the aftercooling process. The yarn has now been gradually cooled to some degree, thus reducing thermal shock. The yarn is directed into carrier tube via roll 121 through primary condenser 122 containing baffles 123124 to form water pool 125 and subsequently into washer-condenser 130. Some steam at reduced pressure from header box 112 flows around baffles 123-124, bubbles through water pool 125 and through primary water sprays 139. i

The yarn is then directed by driven rolls 129 in a downward traversing manner while water sprays from nozzles 138 and the accumulated water flows onto cascade baffles 131, thus washing and scrubbing theexcess dyes and chemicals from the yarn. As can beseen from the drawing, the yarn thus follows a tortuous or zigzag path. The water sprays of nozzles 138 and the water cascading off baffles 131 form a condenser that, completely condenses any steam flowing from the pres-.

sure systems. Air is eliminated by air vents 133. Access hatches 134 provide access for threading the yarns- The washing and condensing water enters the washer-condenser via aftercooler connection 115 through valve that automatically modulates the water flow to effect a final atmospheric pressure within the washer-condenser. This controlled flow water is directed to nozzles 139 and 138 by distributing header 141.

Hot wash water accumulates in the lower portion of the washer-condenser and flows to approximately an equal level into expansion tank (shown in FIG. 6)

via connection 151 through which the yarn is directed. The yarn exits the system up through the wash water in.

tank 150 and passes through driven squeeze rollers 152 whereby excessive water is removed. The dyed and washed yarns travel to external roll-up or batching ma chines and then to subsequent dryers.

Referring to the water recovery and recirculation system of FIG. 6, dirty hot wash water rises inside tank 150 and flows through tandem filters 154 into the make-up mixing section 155, mixes with an amount of cold make-up fresh water from supply pipe 156 and then flows into circulation pump 157. Cold make-up 9 water 156 is directed near the pump suction so as to reduce chances of pump cavitation in pumping hot water. The pump may require location in a pit for higher positive suction heads that may be necessary.

Overflow connection 160 discharges dirty excess wash water to a drain with the excess water resulting from cold make-up water introduction l56 and from collection of steam condensate. Pump 157 forces hot circulating water through a check valve and pipe 161 to an external heat reclaiming exchanger whereby this usable heat is recovered for various other uses, such as preheating make-up air for a yarn dryer, or heating other water systems, etc. In order to maintain a closed system the cooled water is then directed by pump 157 back to heat exchanger 19 by a pipe not shown.

It is noted, however, that the objects of the present invention may still be accomplished by having the washer-condenser cascade apparatus or other suitable washer outside the enclosed system. Similarly the steam may be condensed in a separate condenser or vented to the atmosphere. It is noted, however, that in the latter case the benefits of economical recycling of water will not be attained.

In the process of this invention, the heat setting, dyeing and fixation steps are carried out continuously under elevated temperatures and a saturated steam pressure environment in an entirely enclosed system; the enclosed system even includes the washing and drying steps. By an enclosed system, it is meant to describe an apparatus which has no leaks or holes leading to the outside atmosphere which would allow escape of the steam and decrease in temperature. The apparatus of the present invention is totally pressure sealed against escape of steam. The entrance and exit thermodymamic seals are provided by the heat exchanger 19 and the aftercooler 110, header box 112, and washer condenser 130. Thus, yarn strands treated by the process of this invention enter the system dry from packages and exit in heat set, dyed solid shades and/or multicolor space dyed, and in a washed clean condition without being exposed outside the machine.

Fibers and yarns suitable for dyeing by the process of this invention include natural fibers such as cotton, wool, and jute and synthetic materials such as nylon, polyester and various other fibers particularly suitable for making carpets, knitting yarn, web, such as seat belts, and other manufactured products.

Dyes can be selected from a wide variety, and preferred dyes are acid dyes with water vehicles containing acetic and formic acids as pI-I controllers.

The temperature and internal saturated steam conditions during the dyeing and fixation can vary over wide limits and are essentially limited to the thermal limits of the yarns and dyestuffs used. Generally, operating temperatures of from about 300 to about 400F at about 30 to about 250 psia can be used, and preferably where polyesters are processed, the operation can be conducted at about 300F and about 67 psia.

Also, yarns heat set externally prior to entering the apparatus of this invention for dyeing can be made to retain its previous heat set or texturizing by varying and controlling the temperature process in this apparatus to a lower level than the prior heat set temperature.

What is claimed is:

1. In a process for treating yarn in a steam atmosphere at elevated pressure maintained in an enclosure the steps comprising feeding a continuous length of yarn from a first low pressure zone through a seal into a chamber portion of the enclosure, applying dye to the yarn in the chamber portion, subsequently passing the yarn through a sequence of tubes each of which has an end in communication with the chamber portion, heating the yarn passing through said tubes by passing steam in contact with the exterior of the tubes at a higher pressure and temperature than exists in the enclosure, and passing the yarn leaving the last tube of the sequence through a seal to a second low pressure zone.

2. Ina process for treating yarn in a steam atmosphere at elevated pressure the steps comprising passing a continuous length of yarn into and out of a pressurized steam atmosphere within an enclosure through entry and exit passageways which communicate at one end with the interior of the enclosure and at the other end with zones of lower pressure, the entry passageway including a plurality of parallel coextensive tubes through which the yarn travels sequentially in back and forth directions; continuously cooling the passageways with cooling water to condense substantially all steam in the passageways so as to prevent the passage of appreciable steam into the zones of lower pressure; and washing the treated yarn with at least a portion of the cooling water which has been warmed during the cooling step.

3. A process as in claim 2 including the step of applying dye to the yarn as it passes through the pressurized steam atmosphere.

4. In a process for treating yarn in a steam atmosphere at elevated pressure the steps comprising passing a continuous length of yarn into and out of a pressurized steam atmosphere within an enclosure through entry and exit passageways which communicate at one end with the interior of the enclosure and at the other end with zones of lower pressure; introducing steam into the enclosure through a venturi, the yarn simultaneously passing from the entry passageway through the venturi into the steam pressurized enclosure; continuously cooling the passageway with cooling water to condense substantially all steam in the passageways so as to prevent the passage of appreciable steam into the zones of lower pressure; and washing the treated yarn with at least a portion of the cooling water which has been warmed during the cooling step.

5. A process as in claim 4 including the step of applying dye to the yarn as it passes through the pressurized steam atmosphere.

6. In a process for treating yarn in a steam atmosphere at elevated pressure maintained in an enclosure the steps of: passing high pressure steam through a pressure reducing device into the enclosure to maintain said elevated pressure in the enclosure; passing a continuous length of yarn into the enclosure via a first zone of lower pressure which communicates with the elevated steam pressure atmosphere, the yarnpassing through the steam pressure reducing device simultaneously with the steam; cooling said first zone to condense steam passing thereinto from the elevated steam pressure atmosphere and to thereby maintain said lower pressure; passing the yarn while in the enclosure in indirect heat exchange relationship with high pressure steam to thereby increase the temperature of the yarn; passing the yarn out of the enclosure via a second zone of lower pressure which communicates with the elevated steam atmosphere in the enclosure; and cooling said second zone to condense steam passing thereinto from the elevated steam pressure atmosphere and to thereby maintain said lower pressure in said second zone.

7. A process as in claim 6 wherein the cooling of said first zone of lower pressure is effected with a stream of cooling water, said process including the further step of subsequently passing the stream of cooling water in direct contact with the yarn after the latter has been heated in order to wash the same.

8. A process as in claim 6 wherein the washing step is carried out at least partially in said second zone of lower pressure, said stream of water thereby contacting and aiding in the condensing of steam passing into said second zone from the enclosure.

9. In a process for treating yarn in a steam atmosphere at elevated pressure maintained in an enclosure the steps of passing a continuous length of yarn into the enclosure via a first zone of lower pressure which communicates with the elevated steam pressure atmosphere, cooling said first zone to condense steam passing thereinto from the elevated steam pressure atmosphere and to thereby maintain said lower pressure, passing high pressure steam through a pressure reducing device into the enclosure to maintain said elevated pressure in the enclosure, applying dye to the yarn in 10. A process as in claim 9 wherein the cooling of said first zone of lower pressure is effectedwith a stream ofcooling water, said process including the fur- I ther step of subsequently passing the stream of cooling water in direct contact with the yarn after the latter has been heated in order to wash the same.

11. A process as in claim 9 wherein the washing step is carried out at least partially in said second zone of lower pressure, said stream of water thereby contacting and aiding in the condensing of steam passing into said second zone from the enclosure. 

1. IN A PROCESS FOR TREATING YARN IN A STEAM ATMOSPHERE AT ELEVATED PRESSURE MAINTAINED IN AN ENCLOSURE THE STEPS COMPRISING FEEDING A CONTINUOUS LENGTH OF YARN FROM A FIRST LOW PRESSURE ZONE THROUGH A SEAL INTO A CHAMBER PORTION OF THE ENCLOSURE, APPLYING DYE TO THE YARN IN THE CHAMBER PORTION, SUBSEQUENTLY PASSING THE YARN THROUGH A SEQUENCE OF TUBES EACH OF WHICH HAS AN END IN COMMUNICATION WITH TH THE CHAMBER PORTION, HEATING THE YARN PASSING THROUGH SAID TUBES BY PASSING STEAM IN CONTACT WITH THE EXTERIOR OF THE TUBES AT A HIGHER PRESSURE AND TEMPERATURE THAN EXISTS IN THE ENCLOSURE, AND PASSING THE YARN LEAVING THE LAST TUBE OF THE SEQUENCE THROUGH A SEAL TO A SECOND LOW PRESSURE ZONE.
 2. In a process for treating yarn in a steam atmosphere at elevated pressure the steps comprising passing a continuous length of yarn into and out of a pressurized steam atmosphere within an enclosure through entry and exit passageways which communicate at one end with the interior of the enclosure and at the other end with zones of lower pressure, the entry passageway including a plurality of parallel coextensive tubes through which the yarn travels sequentially in back and forth directions; continuously cooling the passageways with cooling water to condense substantially all steam in the passageways so as to prevent the passage of appreciable steam into the zones of lower pressure; and washing the treated yarn with at least a portion of the cooling water which has been warmed during the cooling step.
 3. A process as in claim 2 including the step of applying dye to the yarn as it passes through the pressurized steam atmosphere.
 4. In a process for treating yarn in a steam atmosphere at elevated pressure the steps comprising passing a continuous length of yarn into and out of a pressurized steam atmosphere within an enclosure through entry and exit passageways which communicate at one end with the interior of the enclosure and at the other end with zones of lower pressure; introducing steam into the enclosure through a venturi, the yarn simultaneously passing from the entry passageway through the venturi into the steam pressurized enclosure; continuously cooling the passageway with cooling water to condense substantially all steam in the passageways so as to prevent the passage of appreciable steam into the zones of lower pressure; and washing the treated yarn with at least a portion of the cooling water which has been warmed during the cooling step.
 5. A process as in claim 4 including the step of applying dye to the yarn as it passes through the pressurized steam atmosphere.
 6. In a process for treating yarn in a steam atmosphere at elevated pressure maintained in an enclosure the steps of: passing high pressure steam through a pressure reducing device into the enclosure to maintain said elevated pressure in the enclosure; passing a continuous length of yarn into the enclosure via a first zone of lower pressure which communicates with the elevated steam pressure atmosphere, the yarn passing through the steam pressure reducing device simultaneously with the steam; cooling said first zone to condense steam passing thereinto from the elevated steam pressure atmosphere and to thereby maintain said lower pressure; passing the yarn while in the enclosure in indirect heat exchange relationship with high pressure steam to thereby increase the temperature of the yarn; passing the yarn out of the enclosure via a second zone of lower pressure which communicates with the elevated steam atmosphere in the enclosure; and cooling said second zone to condense steam passing thereinto from the elevated steam pressure atmosphere and to thereby maintain said lower pressure in said second zone.
 7. A process as in claim 6 wherein the cooling of said first zone of lower pressure is effected with a stream of cooling water, said process including the further step of subsequently passing the stream of cooling water in direct contact with the yarn after the latter has been heated in order to wash the same.
 8. A process as in claim 6 wherein the washing step is carried out at least partially in said second zone of lower pressure, said stream of water thereby contacting and aiding in the condensing of steam passing into said second zone from the enclosure.
 9. In a process for treating yarn in a steam atmosphere at elevated pressure maintained in an enclosure the steps of passing a continuous length of yarn into the enclosure via a first zone of lower pressure which communicates with the elevated steam pressure atmosphere, cooling said first zone to condense steam passing thereinto from the elevated steam pressure atmosphere and to thereby maintain said lower pressure, passing high pressure steam through a pressure reducing device into the enclosure to maintain said elevated pressure in the enclosure, applying dye to the yarn in the enclosure, then passing the yarn while in the enclosure in indirect heat exchange relationship with high pressure steam to thereby increase the temperature of the yarn, passing the yarn out of the enclosure via a second zone of lower pressure which communicates with the elevated steam atmosphere in the enclosure, and cooling said second zone to condense steam passing thereinto from the elevated steam pressure atmosphere and to thereby maintain said lower pressure in said second zone.
 10. A process as in claim 9 wherein the cooling of said first zone of lower pressure is effected with a stream of cooling water, said process including the further step of subsequently passing the stream of cooling water in direct contact with the yarn after the latter has been heated in order to wash the same.
 11. A process as in claim 9 wherein the washing step is carried out at least partially in said second zone of lower pressure, said stream of water thereby contacting and aiding in the condensing of steam passing into said second zone from the enclosure. 